This invention relates to coil components mainly intended for the control of common-mode noise in power supply input circuits of desktop electronic apparatus such as notebook type computers, word processors, and game machines, especially personal computers.
There are two prior art types of coil components. One type has a structure such that a bobbin that carries windings is fitted in a pot core half, coil terminals are pulled out of through holes or through grooves, and another pot core half is fitted over them (Japanese Utility Model Application Kokai No. 5-66922). The other type has grooves formed in the rim of a pot core, through which terminals are pulled out and then a plate cover core is joined to the pot core (Japanese Utility Model Application Kokai No. 59-46021). The former type of Utility Model Application Kokai No. 5-66922, as illustrated in FIGS. 17 and 18, is a magnetic core made up of two core halves 5 joined top to top, each of which being a pot core half consisting of an inner post 1, a wall 2, and a bottom 3 which has through holes 4. A bobbin 7 including windings 6 is fitted in the annular space defined in the pot core halves 5, and pin terminals 8, 8 of the bobbin windings are drawn out via the through holes 4 or, alternatively, end portions of the bobbin windings are bent and pulled out of the core by way of through grooves (not shown). According to the latter type of Utility Model Application Kokai No. 59-46021, as shown in FIG. 19, grooves are formed in the rim of the wall 2 of a pot core 5, and winding terminals 8, 8 are drawn out through the grooves between the pot wall and a cover core 11. In both types the terminals of wirings protrude out of the core through the holes or grooves.
With the tendency toward smaller electronic equipment, planar mounting of their components is acquiring growing importance. The technology is required for a broad range of applications, from micro-current lines to power-supply circuits in which large current flows, or even to battery peripherals. However, planar mounting of large-current components has been hampered by the lack of an adequate technique for thick conductor fabrication. Even today, components of lead-mount type are predominant and, because their externally protruding terminals keep them from being directly mounted on and soldered to circuit boards, they place obstacles in the way of simplification of component mounting process and miniaturization of equipment.